1. Field of the Invention
The present invention relates to a power supply apparatus, and especially relates to a power supply apparatus with extending a hold up time function.
2. Description of the Related Art
The design of the hold up time of the related art power supply is based on the capacitor energy-storage formula: (½)C(V22−V12)=PT, wherein the C means the bulk capacitor, the V2 means the operating voltage, the V1 means the cut-off voltage, the P means the output power of the power supply, and the T means the hold up time. According to the formula mentioned above, in order to extend the hold up time effectively, the research personnel will increase the bulk capacitor. However, the design of the modern power supply is slimmer and lighter today. The bulk capacitor has a larger volume, so that increasing the bulk capacitor is not practical for the modern power supply. This problem needs to be resolved.